首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   724篇
  免费   23篇
  国内免费   2篇
电工技术   4篇
化学工业   154篇
金属工艺   10篇
机械仪表   4篇
建筑科学   32篇
矿业工程   4篇
能源动力   50篇
轻工业   148篇
水利工程   4篇
石油天然气   6篇
无线电   21篇
一般工业技术   74篇
冶金工业   99篇
自动化技术   139篇
  2024年   4篇
  2023年   9篇
  2022年   23篇
  2021年   33篇
  2020年   15篇
  2019年   19篇
  2018年   21篇
  2017年   18篇
  2016年   14篇
  2015年   8篇
  2014年   25篇
  2013年   46篇
  2012年   38篇
  2011年   52篇
  2010年   30篇
  2009年   45篇
  2008年   35篇
  2007年   28篇
  2006年   30篇
  2005年   32篇
  2004年   26篇
  2003年   17篇
  2002年   17篇
  2001年   4篇
  2000年   13篇
  1999年   4篇
  1998年   8篇
  1997年   15篇
  1996年   9篇
  1995年   12篇
  1994年   12篇
  1993年   8篇
  1992年   7篇
  1991年   4篇
  1990年   4篇
  1988年   4篇
  1986年   3篇
  1985年   6篇
  1984年   5篇
  1983年   3篇
  1982年   7篇
  1981年   2篇
  1980年   4篇
  1979年   6篇
  1978年   7篇
  1977年   3篇
  1976年   4篇
  1972年   3篇
  1969年   1篇
  1955年   1篇
排序方式: 共有749条查询结果,搜索用时 14 毫秒
81.
Twenty-eight experienced handlers, considered the best in two transport companies, were interviewed using a questionnaire consisting of partially closed-ended questions. They had to assess 20 videotape handling sequences showing two different handling methods to determine, for 10 factors and overall, which one was the best. They were asked about the inportance of these factors in their choices of the best method. The aims of the study were to verify whether there was a consensus among experienced handlers as to what was a good handling method and to identify the factors taken into consideration by them. Results show the lack of consensus on the best methods. Handlers favor different strategies depending on the worjk context and their own priorities.  相似文献   
82.
Thek-Delaunay tree extends the Delaunay tree introduced in [1], and [2]. It is a hierarchical data structure that allows the semidynamic construction of the higher-order Voronoi diagrams of a finite set ofn points in any dimension. In this paper we prove that a randomized construction of thek-Delaunay tree, and thus of all the orderk Voronoi diagrams, can be done inO(n logn+k 3n) expected time and O(k2n) expected storage in the plane, which is asymptotically optimal for fixedk. Our algorithm extends tod-dimensional space with expected time complexityO(k (d+1)/2+1 n (d+1)/2) and space complexityO(k (d+1)/2 n (d+1)/2). The algorithm is simple and experimental results are given.This work has been supported in part by the ESPRIT Basic Research Action No. 3075 (ALCOM).  相似文献   
83.
Optimal synthesis of human movement or the prediction of the kinematics of a new movement require not only that the multi-body system be modeled but also that a performance criterion is specified. For sub-maximal movements the selection of a suitable performance criterion, able to generate realistic dynamic behavior is difficult. A two-dimensional simulation model of the take-off phase of a sub-maximal long jump was developed to study the effect of criterion choice on the realism of simulated movements. A parametric optimization technique was employed to obtain solutions to the constrained equations of motion. Seven different criteria were evaluated, by comparing simulated movements with an actual performance, to identify the criterion which most closely approximated that spontaneously minimized by the athlete. Synthesis of the take-off phase of a sub-maximal long jump was found to be sensitive to the chosen criterion, with a criterion based on minimizing joint intersegmental forces found to perform well.  相似文献   
84.
85.
Hyperglycaemia is prevalent in critical illness and increases the risk of further complications and mortality, while tight control can reduce mortality up to 43%. Adaptive control methods are capable of highly accurate, targeted blood glucose regulation using limited numbers of manual measurements due to patient discomfort and labour intensity. Therefore, the option to obtain greater data density using emerging continuous glucose sensing devices is attractive. However, the few such systems currently available can have errors in excess of 20-30%. In contrast, typical bedside testing kits have errors of approximately 7-10%. Despite greater measurement frequency larger errors significantly impact the resulting glucose and patient specific parameter estimates, and thus the control actions determined creating an important safety and performance issue. This paper models the impact of the continuous glucose monitoring system (CGMS, Medtronic, Northridge, CA) on model-based parameter identification and glucose prediction. An integral-based fitting and filtering method is developed to reduce the effect of these errors. A noise model is developed based on CGMS data reported in the literature, and is slightly conservative with a mean Clarke Error Grid (CEG) correlation of R=0.81 (range: 0.68-0.88) as compared to a reported value of R=0.82 in a critical care study. Using 17 virtual patient profiles developed from retrospective clinical data, this noise model was used to test the methods developed. Monte-Carlo simulation for each patient resulted in an average absolute 1-h glucose prediction error of 6.20% (range: 4.97-8.06%) with an average standard deviation per patient of 5.22% (range: 3.26-8.55%). Note that all the methods and results are generalizable to similar applications outside of critical care, such as less acute wards and eventually ambulatory individuals. Clinically, the results show one possible computational method for managing the larger errors encountered in emerging continuous blood glucose sensors, thus enabling their more effective use in clinical glucose regulation studies.  相似文献   
86.
This paper aims at identifying some of the key factors in adopting an organization-wide software reuse program. The factors are derived from practical experience reported by industry professionals, through a survey involving 57 Brazilian small, medium and large software organizations. Some of them produce software with commonality between applications, and have mature processes, while others successfully achieved reuse through isolated, ad hoc efforts. The paper compiles the answers from the survey participants, showing which factors were more associated with reuse success. Based on this relationship, a guide is presented, pointing out which factors should be more strongly considered by small, medium and large organizations attempting to establish a reuse program.  相似文献   
87.
88.
Typical applications and research areas of polymeric biomaterials include tissue replacement, tissue augmentation, tissue support, and drug delivery. In many cases the body needs only the temporary presence of a device/biomaterial, in which instance biodegradable and certain partially biodegradable polymeric materials are better alternatives than biostable ones. Recent treatment concepts based on scaffold‐based tissue engineering principles differ from standard tissue replacement and drug therapies as the engineered tissue aims not only to repair but also regenerate the target tissue. Cells have been cultured outside the body for many years; however, it has only recently become possible for scientists and engineers to grow complex three‐dimensional tissue grafts to meet clinical needs. New generations of scaffolds based on synthetic and natural polymers are being developed and evaluated at a rapid pace, aimed at mimicking the structural characteristics of natural extracellular matrix. This review focuses on scaffolds made of more recently developed synthetic polymers for tissue engineering applications. Currently, the design and fabrication of biodegradable synthetic scaffolds is driven by four material categories: (i) common clinically established polymers, including polyglycolide, polylactides, polycaprolactone; (ii) novel di‐ and tri‐block polymers; (iii) newly synthesized or studied polymeric biomaterials, such as polyorthoester, polyanhydrides, polyhydroxyalkanoate, polypyrroles, poly(ether ester amide)s, elastic shape‐memory polymers; and (iv) biomimetic materials, supramolecular polymers formed by self‐assembly, and matrices presenting distinctive or a variety of biochemical cues. This paper aims to review the latest developments from a scaffold material perspective, mainly pertaining to categories (ii) and (iii) listed above. Copyright © 2006 Society of Chemical Industry  相似文献   
89.
90.
The rules and laws enforced in France in 1977 regarding the policy of old housing renewal have extended public intervention to the whole housing stock built before 1948. It came as a complement to the 1962 Malraux Law which exclusively concerned old city centres whose architectural value was preserved. Has the objective put forward to improve old housing by maintaining their residents (tenants and owner occupiers) been reached? The public policy of old housing renewal and its consequences on social occupancy are analysed in their relation to the ownership structure and to the property strategies of the actors who finance this rehabilitation. The paper examines Nord-Pas-de-Calais, one of the regions in France where the old housing stock is the lowest in quality. As for the social changes in the occupancy of these neighbourhoods, our 1995 study confirmed the results obtained in 1988. Four years after the end of the improvement programmes, these neighbourhoodshave retained a residential function for working-class occupants. However, two new trends emerged. On the one hand, despite a better integration of old housing in the policies implemented by local authorities since the 1982-83 decentralisation law, the incentive role of state aids to renewal is increasingly limited. On the other hand, property disinvestment has only been partially reduced. Some housing units remain unimproved and some buildings remain unoccupied. The housing supply is higher than the demand. Ownership of old housing is undermined by demand for housing estates in suburban areas.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号